Published PCT Application No. WO 2013/189858 A1 describes a method for ascertaining a pressure-volume characteristic of vehicle brakes. In order to ascertain the pressure-volume characteristic of the respective braking system, it is necessary firstly to ascertain by way of a pressure sensor, at several points in time during a braking operation executed by way of the braking system, the pressure values existing at the respective points in time; and at the same time to ascertain, by way of a volume sensor or travel sensor, the brake fluid volume delivered to the braking system at the respective points in time as a result of the braking operation. The respectively ascertained values are then plotted as a pressure-volume characteristic curve. It is then said to be possible to determine, by way of a comparison between the currently plotted pressure-volume characteristic curve and an initial or predefined pressure-volume characteristic, correction factors on the basis of which influencing factors (for example, a temperature, wear, or transverse acceleration) are said to be capable of being filtered out.